Process for stabilizing organophosphorus solutions and imparting rot and flame resistance to organic textile materials

ABSTRACT

COPPER SALTS WERE FOUND TO STABILIZE TETRAKIS (HYDROXYMETHYL) PHOSPHONIUM HYDROXIDE (THPOH)-AMMONIUM HYDROXIDE SOLUTIONS BY FORMATION OF A COMPLEX THEREBY MAKING IT POSSIBLE TO APPLY THPOH TO COTTON FABRIC FROM A SINGLE BATH WITHOUT THE USE OF GASEOUS AMMONIA.

United States Patent 3,625,738 PROCESS FOR STABILIZING ORGANOPHOS- PHORUS SOLUTIONS AND IMPARTING ROT AND FLAME RESISTANCE TO ORGANIC TEXTILE MATERIALS Darrell J. Donaldson, Metairie, and Donald J. Daigle, New Orleans, La., assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed July 28, 1969, Ser. No. 845,562 Int. Cl. C09k 3/28; B44d 1/44; D06m 13/26 U.S. Cl. 117-63 7 Claims ABSTRACT OF THE DISCLOSURE Copper salts were found to stabilize tetrakis('hydroxy- -methyl)phosphoniurn hydroxide (THPOH)-ammonium hydroxide solutions by formation of a complex thereby making it possible to apply THPOH to cotton fabric from a single bath without the use of gaseous ammonia.

A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sub-licenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to a process for rendering organic fibrous materials flame and rot resistant. More particularly, this invention deals with a method for stabilizing systems containing phosphorus and nitrogen compounds by the use of metal salts. The treating of organic materials with this resulting mixture renders them flame and rot resistant.

THPC reacts with NaOH in the pH range of 6 to 10 to attain a weakly basic mixture which contains a number of products some of which are tetrakis(hydroxymethyDphosphonium hydroxide (THPOH), tristhydroxymethyl)phosphine (THP) and other related phosphine and tris(hydroxymethyl)phosphine oxide (THPO). This mixture is referred to as THPOH. In the past, organic materials were rendered flame resistant by treating fabric with the THPOH mixture, partially drying and then chemically curing with anhydrous ammonia. This process required controlling the degree of drying to prevent decomposition of the active phosphorus compound before curing and also necessitated the use of gaseous ammonia. (Gaseous ammonia gives off offensive odors.)

This invention discloses a simplified pad-cure process for the application of THPOH-NH flame retardant to cotton which eliminates the undesirable features mentioned above. This is achieved by adding metal salts to the THPOH solution to produce a system stable in the presense of ammonium hydroxide and other basic nitrogen compounds. Without the metal salt the nitrogen compound reacts immediately upon addition to a THPOH solution to form a white isoluble, polymeric material.

The term fibrous organic material includes any hydrophilic fibrous material, that is, a material that absorbs or absorbs water on most of their surface area such as cotton, rayon, jute, wool, paper, cardboard, and their combination with man-made fibers such as avril, polyester, and the like materials. Chemical and physical modifications of such materials which can be impregnated With a liquid and dried are also included. These organic fibrous materials are not limited to desized, scoured, or bleached materials.

The organic fibrous materials treated with the THPOH metal complex solution can be in the form of free fibers, sliver, yarn, thread, and Woven or nonwoven fabrics. We prefer to use of spun textiles such as threads or woven fabrics.

It is an advantage of the process of this invention that the fibrous organic materials may be processed by any conventional technique employing conventional equipment.

By the process of this invention, the addition of a metal salt to a THPOH solution stablizes the solution and for-ms an insoluble material only by condition of processing. This solution padded on fabric and properly finished renders the fabric rot and flame resistant.

In general terms, the invention can be described as follows:

(1) To a solution containing about 15-50% of THPOH a metal salt from 1% to about 20% is added to obtain the metal phosphorus compound.

(2) To this mixture 135% of concentrated ammonium hydroxide is added.

(3) The organic fibrous material is immersed in these solutions and the excess liquid removed by conventional textile methods to give wet pickups ranging from about 50 to about (4) The material is then cured by any conventional manner such as an oven at temperatures ranging from 100-l80 C. for 1 to 15 minutes. Surface active agents, water repellents, softeners and other textile treating agents may be incorporated in the treating bath.

In the instant process, metal compounds of the formula M X where n=l,2, m:l,2, or 3, M any metal such as copper, zinc, and zirconium, and X any anion as chloride, phosphate, nitrate, sulfate, hydroxide, acetate, bromide, iodide, carbonate, and oxide and the like can be used. Concentrations of metal compound depend on the particular metal salt and the concentration of the phosphorus compound. Molar ratios of from about 1/ l to about U 8 metal salts to THPOH were needed for stabilization but the preferred ratio is 1/4 of metal salt to THPOH.

Nitrogen compounds compatible in this system can be ammonia, ammonium salts, amides and amines. The invention is not limited to these but examples of the preferred compounds are phosphoramide methylolacrylamide, formamide, ethylenediamine, O-phenylenediamine, and l,6-hexamethylenediamine.

The organic fibrous materials so treated retained essentially 100% of their breaking strength after treatment and were flame and rot resistant. 'Rot resistance of the treated cotton textile was determined by burial in soil containing highly active cellulose destroying organisms and samples were removed at various intervals for testing using the AATCC Standard Method 30-1957T. Flame resistance Was determined by the standard vertical flame test according to Federal Specification Method 5902 or the match test which is the angle the fabric must be held to extinguish the flame. A fabric having a angle will normally pass the standard vertical flame test.

The following examples are illustrative of the details of the invention. The term percent refers to percent by weight.

3 EXAMPLE 1 TABLE I Grams THPOH Cone. Cu(NOa)2-3H2O (30% S01) NHtOII Results 1 32 12. Unstable.

3. 3 32 12. 5 Stable.

Cotton fabrics padded with a solution that contained 9.1 g. of copper nitrate, 64 g. of 35 THPOH solution and 26.9 g. of concentrated ammonium hydroxide immediately and after 20 days storage contained the same add-ons and flame resistance. In fact, the fabrics treated with solutions which were 20 days old had slightly higher add-ons than those treated with the solution immediately after preparation. Therefore, this study clearly shows that the solution is quite stable for a long period of time.

EXAMPLE 2 Samples of desized, scoured, and bleached cotton twill were padded with a solution containing 9.1% copper nitrate, 64% THPOH, and 26.9% concentrated NH OH. The samples were cured at temperature ranges from 130 to 160 C. for 5 to minutes in an electric force air oven. The fabric cured at 130 C. had 14.1% add-on, 3.52% phosphorus, and 1.17% copper and after 5 laundering cycles had a char length of 5.5 inches as measured by the standard vertical flame test.

EXAMPLE 3 Cotton fabrics treated in the same manner as in Example 2 except that the samples were placed in a plastic bag for 18 hours at room temperature before curing at 13'0160 C. for 5 to 10 minutes. A fabric cured in this manner at 130 C. had 12.3% add-on, 3.97% phosphorus and 1.31% copper and was still flame resistant after 5 laundering cycles.

EXAMPLE 4 Desized, bleached, and scoured cotton sateen was padded with the following solution: 177.5 g. of 50% THPOH, 26.8 g. of Cu(NO -3H O and 47.2 g. of concentrated ammonium hydroxide and cured at 160 C.

for 10 minutes. The fabric had a 17.7% add-on, 3.76 phosphorus and 1.26% copper. After 25 laundering cycles the fabric passed the standard vertical flame test with a 3.5 inch char length and possessed 3.07% phosphorus and 0.74% copper.

EXAMPLE 5 Cotton twill was padded with a solution that contained 9.1% copper nitrate, 64% of 35% THPOH and 26.9% concentrated ammonium hydroxide to obtain a 70% wet pickup. The fabrics were then cured for 1% to 5 minutes on a tenter frame at 155 C. The treated fabric was rinsed on a jig first with hot water and then with cold water. The cotton fabric cured for 1% minutes at 155 C. possessed 103.5% of its original breaking and passed the standard vertical flame test after 15 laundering cycles with a 3.5 inch char length.

EXAMPLE 6 Cotton twill treated in the same manner as in Example 5 except that it was cured at 155 C. for 5 minutes. The

4 sample after treatment possessed 116% of its original breaking strength and after 25 laundering cycles passed the standard vertical flame test with a 3.5 inch char length. After a 3 hour soap soda boil this fabric also passed the standard vertical flame test with a 4.5 inch char length.

EXAMPLE 7 Cotton twill was treated with same solution as in Example 5 except 9.1% of copper sulfate was used in place of copper nitrate. The fabrics were cured for 2 to 4 minutes at C. on a tenter frame. The fabrics passed the standard vertical flame test after 25 laundering cycles with char length ranging from 4.5 to 5.0 inch.

EXAMPLE 8 A solution containing 5.0 g. copper acetate, 48 g. of 35 THPOH and 20.2 g. of concentrated NH O H was padded on a cotton sample to give about 70-80% Wet pickup and cured for 10 minutes at 150 C. The fabric after washing passed the 180 angle match test.

EXAMPLE 9 A desized, bleached paper sample was treated with a solution containing 9.1 g. Cu( NO )-3H O, 63.7 g. of a 40% THPOH solution and 27.3 g. of concentrated NH OH to give about a 70% wet pickup and cured 10 minutes at 150 C. The sample was washed and allowed to equilibrate with room conditions. The sample when ignited with a match refused to burn in the standard vertical position.

EXAMPLE 10 A wool sample was treated with the same solution as in Example 9 and cured 10 minutes at 150 C. After washing and drying, the sample had about a 30% add-on and failed to burn in the vertical position when ignited with a match.

EXAMPLE 11 Cotton asnaburg was treated with the following solution: 9.1% Cu(NO -3H O, 22.4% THPOH and 26.9% concentrated NH OH to give about a 7080% wet pickup and cured 10- minutes at 130160 C. After washing and drying, the fabric had about 1112% add-on. After 4 weeks soil burial the treated cotton had retained about 40% of its original breaking strength. The control fabric after 4 days had completely disintegrated.

EXAMPLE l2 tDesized, bleached, scoured cotton sateen was treated with a solution containing 64 g. of 35% THPOH solution, 8 g. of Cu(NO -3H O and 28 g. of formamide to give about a 7080% wet pickup and cured at 14 0 C. for 10 minutes. After washing and drying the fabric passed the standard vertical flame test.

We claim:

1. A process for imparting rot and flame resistance to an organic fibrous material comprising:

(a) adding to an aqueous solution containing about from 15 to 50 weight percent of tetrakis(hydroxy methyl)phosphonium hydroxide about from 1 to 20 weight percent of a metallic compound of the formula M X where n is 1 or 2, m is 1, 2, or 3, M is a metal selected from the group consisting of copper, zinc and zirconium, and X is an anion selected from the group consisting of chloride, phosphate, nitrate, sulfate, hydroxide, acetate, bromide, iodide, carbonate, and oxide;

(b) adding to the resulting mixture from (a) about from 1 to 35 weight percent of a nitrogen-containing compound selected from the group consisting of ammonia, ammonium salts, amides, and amines;

(c) impregnating the organic fibrous material with the mixture from (b) to a wet pickup of about from 50 to 110 weight percent;

(d) curing the impregnated material from (c) at a temperature ranging from about 100 C. to 180 C. for about from 1 to 15 minutes; and (e) washing the cured material from (d) free of excess reagents. 2. The process of claim 1 wherein the metal component of the metallic compound is copper.

'3. The process of claim 1 wherein the metallic compound is copper nitrate.

4. The process of claim 1 wherein the metallic compound is copper sulfate.

5. The process of claim 1 wherein the nitrogen-containing compound is concentrated ammonium hydroxide.

6. The process of claim 1 wherein the nitrogen-containing compound is form'amide.

7. The product produced by the process of claim 1.

References Cited UNITED STATES PATENTS 2,772,188 11/1956 Reeves et a1. 117-136 2,795,569 6/1957 Reeves et a1. 117-137 UX 6 2,889,289 6/1959 Reeves et al. l17136 X 2,927,050 3/1960 Reeves et a1 117-137 X 3,236,676 2/1966 Coates et al. 11762.2 3,242,028 3/1966 Hart 11762.2 X 3,332,794 7/1967 Hart 11762.2 X 3,398,019 8/196 8 Langguth et a1. 117137 X 3,420,699 1/1969 Ward et al. 11762.2 X 3,423,230 1/1969 Georges 117 62.2 3,524,761 8/1970 Humphrey 117-138 OTHER REFERENCES Reeves et al., THPOH and ammonia on cotton 15 pp. 42 and 43.

. Chemical and Engineering News, Sept. 9, 1968,

US. Cl. X.R. 

